Background
Patients with proximal femoral neck fracture (hip fracture) represent a growing population with high mortality [
1], high risk of postoperative complications [
2], and impaired quality of life [
3]. In acknowledging the challenges related to the treatment of these patients, a list of quality indicators for the treatment of hip fracture has been created to optimize all modifiable factors associated with the quality of care, including the administration of analgesics [
4]. Factors associated with early mortality have been extensively explored, including age, sex, comorbidity, type of fracture, time to surgery, housing, and preoperative mobility [
5,
6]. Although not directly related to mortality, timely and adequate pain management is essential for early mobilization and recovery [
7] and patients with hip fracture will benefit of prehospital treatment started in the prehospital setting.
Only a few older studies have explored acute prehospital pain management in patients with hip fracture, and they report that less than half of patients had been treated with analgesics during ambulance transport [
8,
9]. Studies in patients with hip fracture have also been conducted in emergency departments, and the findings consistently report undertreatment of pain in these patients [
10‐
12]. In Denmark, the only available opioid administered by ambulance personnel in the prehospital setting is fentanyl [
13,
14]. When dosed and titrated sufficiently, fentanyl is a feasible way of achieving immediate pain relief in patients with hip fracture. However, only a limited number of studies of clinical prehospital care of patients with hip fracture exist. Therefore, the objectives of this study were to determine the prevalence of administration of intravenous fentanyl to patients with hip fracture during ambulance transport in the North Denmark Region and to identify risk factors for analgesic non-treatment. We hypothesized that a low number of patients were treated and that several patient-related factors such as age and comorbidities are associated with non-treatment.
Results
In the 3-year study period, 2,394 patients from the North Denmark Region aged > 65 years and surgically treated for a hip fracture were identified in the Danish Interdisciplinary Hip Fracture Registry. Of these 2,140 patients (89%) were registered as having been transported by ambulance on the day of their hospital admission. Patients not registered in the electronic prehospital patient record (amPHI®) were younger (80.7 years, CI: 79.6-81.7 vs. 83.2 years, CI: 82.9-83.6; P = 0.0001), had fewer displaced fractures (73.2% vs. 80.2%; P = 0.01), were more likely to have medial fractures (63.4% vs. 50.8%; P = 0.003), and were more often examined by a GP on the same day as the hospital admission (31.7% vs. 24.3%; P = 0.01). Registered and non-registered patients were similar in terms of 30-day mortality, sex, CCI score, BMI, housing, and reoperation rate due to complications.
Of the 2,140 transported patients with hip fracture, 584 (27.3%, 95% CI: 25.4-29.2) were treated with intravenous fentanyl. The cumulated median dose of fentanyl was 80 μg (IQR 50–100), administered in 2 doses (IQR 1–2). The pain score was documented in 563 of 2,140 patients (26.3%, 95% CI: 24.4-28.2) and mainly if fentanyl was administered (72.6%, 95% CI: 69.0-76.3). Pain scores were more frequently documented for patients with pertrochanteric (27.6%, 95% CI: 24.7-30.6) and subtrochanteric fractures (33.0%, 95% CI: 26.1-39.9) compared with medial fractures (24.1%, 95% CI: 21.6-26.7,
P = 0.02). For patients with documented pain scores, pain intensity worsened from start of transport (NRS: 5 [IQR 3-8]) to hospital admission (NRS: 6 [IQR 4-8];
P = 0.02). No patients were treated with naloxone, and only a few patients received other prehospital treatments that included anticholinergics (
n = 1), bronchodilators (
n = 6), antiemetics (
n = 25), and nitrous oxide (
n = 16). Risk factors for analgesic non-treatment were older age, male sex (RR 0.77, 95% CI: 0.64-0.91), institutional housing (RR 0.71, 95% CI: 0.56-0.91), medial fracture (RR 0.75, 95% CI: 0.60-0.93), short time with ambulance personnel, low levels of urgency, year of fracture (2011) and if seen by a GP prior to transport. Having at least one comorbidity (CCI score
> 1) was associated with analgesic non-treatment (RR 0.83, 95% CI: 0.72-0.96). the same trend was observed when CCI score was divided into 4, although not statistical significant, (Table
1). Estimates stratified by sex, age and comorbidity are given in Table
2. Estimates were not affected by daily, weekly or seasonal variances (data not shown).
Table 1
The prevalence of fentanyl treatment and potential risk factors of non-treatment
Age (years), n = 2140 |
65-74 | 362 | 34.3 (29.3-39.2) | 1 (reference) | 1 (reference) |
75-79 | 338 | 30.8 (25.8-35.7) | 0.89 (0.72-1.11) | 0.90 (0.73-1.12) |
80-84 | 465 | 26.5 (22.4-30.5) | 0.77 (0.63-0.95) | 0.77 (0.62-0.95) |
85-89 | 527 | 24.1 (20.4-27.8) | 0.70 (0.57-0.87) | 0.72 (0.58-0.89) |
> 90 | 448 | 23.7 (19.7-27.6) | 0.69 (0.55-0.86) | 0.81 (0.65-1.00) |
Sex, n = 2140 |
Female | 1488 | 29.0 (26.7-31.3) | 1 (reference) | 1 (reference) |
Male | 652 | 23.3 (20.1-26.6) | 0.80 (0.68-0.94) | 0.76 (0.64-0.91) |
CCI score, n = 2140 |
0 | 875 | 30.9 (27.8-33.9) | 1 (reference) | 1 (reference) |
1 | 528 | 23.5 (19.9-27.1) | 0.76 (0.63-0.91) | 0.77 (0.63-0.93) |
2 | 340 | 25.0 (20.4-29.6) | 0.81 (0.66-0.99) | 0.86 (0.69-1.07) |
3+ | 397 | 26.4 (22.1-30.8) | 0.86 (0.71-1.04) | 0.90 (0.74-1.09) |
Housing, n = 1967 |
Own home | 1328 | 30.5 (28.0-33.0) | 1 (reference) | 1 (reference) |
OHATI | 210 | 34.8 (28.3-41.3) | 1.14 (0.93-1.40) | 1.30 (1.06-1.60) |
Institution | 429 | 14.0 (10.7-17.3) | 0.46 (0.36-0.59) | 0.71 (0.56-0.91) |
BMI, n = 2140 |
Normal | 1051 | 27.0 (24.3-29.7) | 1 (reference) | 1 (reference) |
Underweight | 191 | 26.7 (20.4-33.0) | 0.99 (0.77-1.28) | 0.99 (0.77-1.29) |
Overweight | 521 | 27.8 (24.0-31.7) | 1.03 (0.87-1.22) | 1.04 (0.88-1.22) |
Obeseb
| 377 | 27.6 (23.1-32.1) | 1.02 (0.84-1.23) | 1.03 (0.82-1.31) |
Fracture displacement, n = 1981 |
Yes | 230 | 23.0 (17.6-28.5) | 1 (reference) | 1 (reference) |
No | 1717 | 27.5 (25.4-29.7) | 0.84 (0.65-1.07) | 1.07 (0.83-1.36) |
Unspecified | 34 | 38.2 (21.0-55.4) | 1.39 (0.90-2.14) | 1.32 (0.85-2.04) |
Type of fracture, n = 2140 |
Subtrochanteric | 182 | 39.0 (31.9-46.2) | 1 (reference) | 1 (reference) |
Pertrochanteric | 872 | 29.5 (26.4-32.5) | 0.76 (0.61-0.93) | 0.88 (0.71-1.09) |
Medial | 1086 | 23.6 (21.0-26.1) | 0.60 (0.49-0.75) | 0.75 (0.60-0.93) |
Prior consultation with GP, n = 2140 |
No | 1622 | 30.4 (28.2-32.6) | 1 (reference) | 1 (reference) |
Yes | 518 | 17.6 (14.3-20.9) | 0.58 (0.47-0.71) | 0.81 (0.66-0.99) |
EMCC triage level, n = 1895 |
A (highest) | 145 | 37.9 (29.9-45.9) | 1 (reference) | 1 (reference) |
B | 1246 | 32.9 (30.3-35.5) | 0.87 (0.69-1.08) | 1.00 (0.81-1.24) |
C | 504 | 11.1 (8.4-13.9) | 0.29 (0.21-0.40) | 0.43 (0.31-0.60) |
Time with ambulance personnelc (minutes), n = 1878 |
< 20 | 174 | 1.7 (0.0-3.7) | 0.04 (0.01-0.11) | 0.02 (0.00-0.12) |
20-29 | 306 | 12.4 (8.70-16.1) | 0.25 (0.18-0.35) | 0.27 (0.19-0.38) |
30-39 | 362 | 21.0 (16.8-25.2) | 0.43 (0.34-0.54) | 0.45 (0.36-0.57) |
40-49 | 377 | 30.0 (25.3-34.6) | 0.61 (0.51-0.74) | 0.64 (0.53-0.78) |
50-59 | 337 | 38.0 (32.8-43.2) | 0.77 (0.65-0.92) | 0.81 (0.68-0.97) |
> 60 | 322 | 49.1 (43.6-54.6) | 1 (reference) | 1 (reference) |
Yeard, n = 2140 |
2011 | 360 | 19.7 (15.6-23.9) | 1 (reference) | 1 (reference) |
2012 | 773 | 29.5 (26.3-32.7) | 1.50 (1.18-1.89) | 1.44 (1.11-1.85) |
2013 | 666 | 28.5 (25.1-32.0) | 1.45 (1.14-1.84) | 1.41 (1.09-1.83) |
2014 | 341 | 27.9 (23.1-32.6) | 1.41 (1.08-1.85) | 1.50 (1.13-2.00) |
Table 2
Risk factors of fentanyl non-treatment stratified by sex, comorbidity and age
Housing, n = 1967 |
Own home | 97/391 | 1 (reference) | 309/937 | 1 (reference) | 203/598 | 1 (reference) | 202/730 | 1 (reference) | 260/815 | 1 (reference) | 145/513 | 1 (reference) |
OHATI | 22/69 | 1.36 (0.87-2.13) | 51/141 | 1.28 (1.02-1.60) | 29/71 | 1.41 (1.01-1.95) | 44/139 | 1.27 (0.97-1.66) | 35/91 | 1.26 (0.95-1.69) | 38/119 | 1.26 (0.94-1.71) |
Institution | 25/136 | 1.10 (0.73-1.68) | 35/293 | 0.58 (0.43-0.80) | 17/140 | 0.55 (0.34-0.89) | 43/289 | 0.80 (0.59-1.07) | 25/163 | 0.67 (0.46-0.97) | 35/266 | 0.71 (0.51-0.99) |
BMI, n = 2140 |
Normal | 69/303 | 1 (reference) | 215/748 | 1 (reference) | 139/454 | 1 (reference) | 34/120 | 1 (reference) | 164/545 | 1 (reference) | 120/506 | 1 (reference) |
Underweight | 10/27 | 1.03 (0.50-2.12) | 41/164 | 0.96 (0.73-1.26) | 17/71 | 0.94 (0.61-1.45) | 145/597 | 1.02 (0.74-1.41) | 23/84 | 0.91 (0.64-1.31) | 28/107 | 1.19 (0.82-1.74) |
Overweight | 44/198 | 0.81 (0.56-1.17) | 101/323 | 1.13 (0.94-1.35) | 67/206 | 1.07 (0.85-1.36) | 78/315 | 1.00 (0.79-1.26) | 93/308 | 0.99 (0.80-1.21) | 52/213 | 1.13 (0.86-1.50) |
Obesea
| 29/124 | 1.11 (0.70-1.76) | 75/253 | 0.98 (0.74-1.29) | 47/144 | 1.00 (0.73-.138) | 57/233 | 1.06 (0.76-1.48) | 71/228 | 0.98 (0.75-1.30) | 33/149 | 1.21 (0.78-1.87) |
Fracture displacement, n = 1981 |
Yes | 126/519 | 1 (reference) | 347/1198 | 1 (reference) | 221/705 | 1 (reference) | 252/1012 | 1 (reference) | 283/924 | 1 (reference) | 190/793 | 1 (reference) |
No | 16/75 | 0.99 (0.57-1.74) | 37/155 | 1.10 (0.83-1.44) | 19/91 | 0.88 (0.59-1.32) | 34/139 | 1.19 (0.87-1.63) | 34/127 | 1.12 (0.83-1.52) | 19/103 | 0.99 (0.63-1.56) |
Unspecified | 2/10 | 0.96 (0.27-3.21) | 11/24 | 1.43 (0.92-2.21) | 8/17 | 1.33 (0.81-2.17) | 5/17 | 1.29 (0.53-3.16) | 7/20 | 1.01 (0.57-1.77) | 6/14 | 1.87 (0.95-3.68) |
Type of fracture |
Subtrochanteric | 22/60 | 1 (reference) 0.76 | 49/122 | 1 (reference) | 33/66 | 1 (reference) | 38/116 | 1 (reference) | 44/102 | 1 (reference) | 27/80 | 1 (reference) |
Pertrochanteric | 67/276 | (0.49-1.16) | 190/596 | 0.93 (0.73-1.20) | 114/353 | 0.71 (0.52-0.96) | 143/519 | 0.79 (0.58-1.07) | 134/444 | 0.81 (0.61-1.06) | 123/428 | 0.89 (0.62-1.28) |
Medial | 63/316 | 0.70 (0.45-1.09) | 49/122 | 0.77 (0.60-0.99) | 123/456 | 0.84 (0.62-1.14) | 133/630 | 0.92 (0.68-1.25) | 173/619 | 0.75 (0.57-0.99) | 83/467 | 0.66 (0.45-0.96) |
Prior consultation with GP |
No | 116/302 | 1 (reference) | 366/1134 | 1 (reference) | 234/678 | 1 (reference) | 259/944 | 1 (reference) | 303/923 | 1 (reference) | 190/699 | 1 (reference) |
Yes | 8/60 | 0.56 (0.33-0.92) | 66/354 | 0.91 (0.73-1.14) | 36/197 | 0.75 (0.54-1.04) | 55/321 | 0.87 (0.67-1.14) | 48/242 | 0.83 (0.63-1.10) | 43/276 | 0.71 (0.51-0.98) |
EMCC triage level |
A (highest) | 17/45 | 1 (reference) | 39/88 | 1 (reference) | 32/68 | 1 (reference) | 23/77 | 1 (reference) | 42/106 | 1 (reference) | 13/39 | 1 (reference) |
B | 87/202 | 1.31 (0.84-2.06) | 317/897 | 0.88 (0.70-1.11) | 189/516 | 0.99 (0.76-1.28) | 221/730 | 1.08 (0.75-1.55) | 243/679 | 1.00 (0.77-1.29) | 167/567 | 0.97 (0.66-1.45) |
C | 10/72 | 0.68 (0.36-1.27) | 37/344 | 0.34 (0.23-0.50) | 19/190 | 0.32 (0.19-0.55) | 37/314 | 0.55 (0.34-0.88) | 32/241 | 0.47 (0.31-0.70) | 24/263 | 0.40 (0.23-0.72) |
Time with ambulance personnelb, minutes |
<20 | 2/29 | 0.07 (0.01-0.51) | 0/125 | - | 3/67 | 0.04 (0.01-0.30) | 0/107 | - | 3/88 | 0.03 (0.01-0.21) | 0/86 | - |
20-29 | 8/47 | 0.28 (0.14-0.54) | 30/217 | 0.26 (0.18-0.39) | 20/126 | 0.31 (0.20-0.49) | 18/180 | 0.23 (0.14-0.38) | 27/162 | 0.32 (0.22-0.48) | 11/144 | 0.19 (0.10-0.35) |
30-39 | 15/52 | 0.62 (0.38-1.00) | 55/267 | 0.42 (0.32-0.55) | 39/146 | 0.53 (0.39-0.73) | 37/216 | 0.38 (0.26-0.54) | 44/183 | 0.46 (0.34-0.62) | 32/179 | 0.45 (0.31-0.65) |
40-49 | 23/57 | 0.83 (0.56-1.23) | 78/255 | 0.59 (0.47-0.74) | 49/161 | 0.64 (0.48-0.85) | 64/216 | 0.65 (0.50-0.85) | 65/196 | 0.63 (0.49-0.81) | 48/181 | 0.64 (0.47-0.89) |
50-59 | 24/62 | 0.78 (0.51-1.19) | 103/236 | 0.82 (0.67-0.99) | 59/143 | 0.81 (0.62-1.04) | 69/194 | 0.82 (0.64-1.06) | 74/189 | 0.72 (0.58-0.91) | 54/148 | 0.96 (0.73-1.28) |
>60 | 41/71 | 1 (reference) | 121/218 | 1 (reference) | 68/124 | 1 (reference) | 90/198 | 1 (reference) | 100/198 | 1 (reference) | 58/124 | 1 (reference) |
Yearc
|
2011 | 20/106 | 1 (reference) | 51/254 | 1 (reference) | 36/163 | 1 (reference) | 35/197 | 1 (reference) | 47/211 | 1 (reference) | 24/149 | 1 (reference) |
2012 | 61/240 | 1.44 (0.85-2.44) | 167/533 | 1.47 (1.10-1.96) | 106/307 | 1.60 (1.12-2.31) | 122/466 | 1.24 (0.87-1.78) | 145/427 | 1.43 (1.07-1.92) | 83/346 | 1.47 (0.89-2.43) |
2013 | 51/211 | 1.23 (0.72-2.11) | 139/455 | 1.50 (1.12-2.01) | 81/257 | 1.49 (1.02-2.17) | 109/409 | 1.30 (0.91-1.87) | 109/350 | 1.33 (0.98-1.81) | 81/316 | 1.61 (0.98-2.64) |
2014 | 20/95 | 1.48 (0.79-2.76) | 75/246 | 1.55 (1.13-2.13) | 47/148 | 1.60 (1.06-2.41) | 48/193 | 1.37 (0.91-2.04) | 50/177 | 1.28 (0.90-1.81) | 45/164 | 1.96 (1.16-3.31) |
Sex |
Female | - | - | - | - | 210/666 | 1 (reference) | 222/822 | 1 (reference) | 260/764 | 1 (reference) | 172/724 | 1 (reference) |
Male | | | | | 60/209 | 0.83 (0.64-1.07) | 92/443 | 0.71 (0.56-0.90) | 91/401 | 0.70 (0.56-0.87) | 61/251 | 0.89 (0.67-1.19) |
CCI score |
0 | 60/209 | 1 (reference) | 210/666 | 1 (reference) | - | - | - | - | 159/433 | 1 (reference) | 111/442 | 1 (reference) |
1 | 31/155 | 0.63 (0.41-0.97) | 93/373 | 0.82 (0.66-1.02) | | | | | 70/287 | 0.69 (0.54-0.90) | 54/241 | 0.87 (0.65-1.16) |
2 | 29/121 | 0.80 (0.54-1.19) | 56/219 | 0.82 (0.63-1.07) | | | | | 52/204 | 0.79 (0.61-1.04) | 33/136 | 0.94 (0.65-1.37) |
3+ | 32/167 | 0.66 (0.44-1.00) | 73/230 | 1.00 (0.81-1.24) | | | | | 70/204 | 0.87 (0.69-1.10) | 35/156 | 0.88 (0.63-1.24) |
Age, years |
65-74 | 37/144 | 1 (reference) | 87/218 | 1 (reference) | 67/155 | 1 (reference) | 57/207 | 1 (reference) | - | - | - | - |
75-79 | 26/108 | 0.85 (0.53-1.38) | 78/230 | 0.92 (0.72-1.18) | 37/115 | 0.71 (0.50-1.01) | 67/223 | 1.08 (0.80-1.45) | | | | |
80-84 | 28/149 | 0.64 (0.40-1.04) | 95/316 | 0.84 (0.66-1.06) | 55/163 | 0.78 (0.58-1.05) | 68/302 | 0.78 (0.56-1.08) | | | | |
85-89 | 45/158 | 0.94 (0.63-1.40) | 82/369 | 0.65 (0.50-0.84) | 58/219 | 0.61 (0.45-0.84) | 69/308 | 0.81 (0.59-1.12) | | | | |
>90 | 16/93 | 0.59 (0.32-1.11) | 90/355 | 0.86 (0.68-1.09) | 53/223 | 0.76 (0.57-1.01) | 53/225 | 0.90 (0.65-1.28) | | | | |
Discussion
In this large multicenter, observational study involving 2,140 patients with hip fracture, we found that only 27% of the patients were treated with intravenous fentanyl, and pain scores were high, though only reported in a small fraction of patients. Advanced age, male sex, institutional housing, medial fracture, short time with ambulance personnel, low levels of urgency, year of fracture (2011) and if seen by a GP prior to transport were associated with analgesic non-treatment.
Our results agree with the findings reported in the limited existing literature. A small retrospective medical chart review study of 128 Australian patients with hip fracture found that only half of the patients had received prehospital intravenous morphine [
8]. A similar prevalence of prehospital analgesic treatment was found in a more recent multicenter study of 646 patients with hip fracture by reviewing the patterns of prehospital and emergency department analgesia [
9]. Neither studies were able to provide a valid assessment of risk factors for analgesic non-treatment.
Platts-Mills and colleagues assessed a large heterogeneous group of prehospital patients transported by ambulance and found a negative association between advanced age (≥65 years compared with 18–64 years) and the likelihood of receiving analgesics [
23]. Similar findings have been reported in other acute prehospital and emergency department settings [
24‐
26]. For all five studies, a high number of patients were excluded because of missing data, and their results should therefore be interpreted cautiously. Even though not elucidated clearly in our results, a possible explanation for the low prevalence of treatment among older people is that, they were not asked about pain as indicated by the low number of pain scores. As pain scores were not documented systematically a reliable description of pain intensity was therefore not possible. Hwang et al. systematically assessed 158 patients with hip fracture in an emergency department and found that 81% complained of pain, proposing that the vast majority of these patients still needed analgesic treatment [
12]. Our data showed that patients with some types of fractures (medial) were less likely to receive fentanyl and thus less likely to have a documented pain score compared with those with other types (subtrochanteric), suggesting that pain levels vary according to the specific fracture type. Even though these fractures vary within age groups, our analyses were adjusted for multiple confounders, including age. Another explanation for non-treatment, among a subgroup of the old patients may be their inability to express pain and analgesic requirements because of cognitive impairments [
11]. This seems to be somewhat supported by our results, indicating that patients living in institutions were less likely to receive fentanyl compared with patients living in their own homes. A third explanation could be the complex age-related pathophysiological changes in the peripheral and central nervous system that modulate the response to noxious stimuli, leading to altered pain perception and lower levels of acute pain [
27].
We found that male patients were less likely to receive intravenous fentanyl than women, which has not been observed in similar studies [
8,
9]. This finding is in contrast to three larger prehospital studies on patients with acute pain, finding that females were less likely to receive opioid treatment for various reasons [
23,
26,
28]. The gender difference in pain research has been extensively explored without reaching any firm conclusions. Some findings show that women report pain more frequently and might experience more severe clinical pain [
29]. This could explain the findings in our study if ambulance professionals administered fentanyl on request from female patients.
We found that patients given the lowest level of urgency (C) by the EMCC were less likely to receive fentanyl compared with those given the highest level of urgency (A). One possible explanation might be that patients or relatives that express pain more explicitly tend to be given priority by the EMCC and the treating ambulance professionals. In contrast, one study on 1,246 emergency callers found no association between pain severity and the prioritization of the dispatch responses [
30].
Non-treatment was associated with increased comorbidity in terms of CCI score
> 1, although not significant when divided into 4 strata (CCI score 0,1,2 and 3+). The CCI score was initially intended to predict in-hospital mortality among medical patients [
6,
16] but the potential role of the CCI score in predicting analgesic non-treatment in a prehospital setting has never been explored and should, therefore, be interpreted carefully. It can be argued that patients with comorbidities tend to be more prone to take prescription drugs that potentially interact with opioids. Because ambulance professionals are taught to be cautious with these patients, one would expect to find a lower prevalence of analgesic treatment in patients with comorbidities. The absence of such association can partly be a consequence an insufficient sample size; thus, future research is needed to address this issue. Finally, BMI was not associated with non-treatment, even though it would have been expected that obtaining intravenous access could be more difficult with extreme body weights [
31,
32].
As for other observational studies, it can only be speculated why some of the presented explanatory variables are associated with analgesic non-treatment. Acute pain is a subjective experience with multiple biological, socioeconomic, and psychological contributing factors that most likely differ within various strata of patient characteristics, of which some may not be measured quantitatively. The decision of whether to treat acute pain also relies on numerous considerations made by the ambulance personnel, including the fear of inducing adverse effects or priority given to other aspects of treatment when time is critical [
33,
34].
Taking these possible explanations into account, continued education of ambulance personnel in sufficiently assessing and treating patients with hip fracture is needed. Additionally, future studies should address alternative/supportive pain treatment modalities with adequate analgesic properties and limited side effects that can be handled satisfactorily by ambulance personnel. Other formulas of opioids with faster onset and shorter analgesic duration could theoretically ease titration [
21]. An alternative treatment approach in patients with hip fractures is peripheral nerve blockades, which could prolong the desired analgesic effect and optimize the continuum of patient care from the accident until the initiation of surgery [
35]. Nerve blockades could be applied in prehospital settings with advanced care, but this would require discussions of economic and clinical priorities [
36‐
39]. The optimal prehospital treatment in terms of efficacy and safety should be based on results from double-blind randomized controlled trials.
In addition to the large sample size, the strengths of our study are that it included patients who represent real-world population-based data from an entire region. The limitations discussed below reflect its register-based observational design. First, selection was present because patients not registered in the electronic prehospital patient record were younger, had fewer displaced fractures, were more likely to have medial fractures, and were more often examined by a GP on the day of their hospital admission. However, probably this reflects the fact that these patients reached the hospital by means other than ambulance. It can therefore be argued that our final patient cohort represents the typical patient with hip fracture transported by ambulance and that selection bias is a minor concern. Supportively, the population-based design and the free access to health care including emergency medical services minimize the risk of selection bias. Second, information bias cannot be ruled out because erroneous coding of analgesic administration in acute settings is a potential risk [
24]. Therefore, the true prevalence of fentanyl administration in ambulances might be slightly higher. Probably, as coding errors would not be unevenly distributed within any of our explanatory variables, potential misclassifications would be non-differential and could bias the results towards the null. Third, although our explanatory variables were adjusted for several potential confounders, relevant unmeasured variables would still be able to affect our estimates. Fourth, in contrast to the treatment protocol prescriptions pain scores were not documented systematically and therefore, a thorough description of pain intensity was not achievable. Imputation was not possible since pain scores were mainly available for patients treated with fentanyl and thereby not missing at random [
40]. Last, the association between prior consultation with a GP and lower odds of receiving fentanyl in the ambulance might mirror the fact that patients were treated with opioids by the GP and therefore did not need further analgesics. The database containing information on GP consultations did not have detailed information on treatment, so this factor remains unexplored.
Conclusion
In this prehospital study exploring transported patients with hip fracture, a small fraction of patients were treated with intravenous fentanyl, and risk factors for analgesic non-treatment included advanced age, male sex, comorbidity, institutional housing, medial fracture, short time with ambulance personnel, low level of urgency assessed at the EMCC, year of fracture (2011) and if seen by a GP prior to transport. These findings give insight into the factors associated with analgesic non-treatment and these need to be taken into account in future studies and clinical care. Improvement of treatment involves several aspects of care, such as education of health care providers and clinical audits on treatment strategies. Future prospective studies should attempt to address covariates of socioeconomic, cultural, and psychological origin to provide further insight into the multifactorial causes of analgesic non-treatment.
Acknowledgements
The authors thank:
Helle O. Andersen for English language revision, Thomas Mulvad Larsen for supervision and advice during data processing and Poul Anders Hansen for brilliant collaboration in all the stages of this project.